octeontx2-af: cn10k: Do not enable RPM loopback for LPC interfaces

Internal looback is not supported to low rate LPCS interface like
SGMII/QSGMII. Hence don't allow to enable for such interfaces.

Fixes: 3ad3f8f9 ("octeontx2-af: cn10k: MAC internal loopback support")
Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeontx2/af/rpm.c

@@ -291,7 +291,12 @@ int rpm_lmac_internal_loopback(void *rpmd, int lmac_id, bool enable)
 	if (!rpm || lmac_id >= rpm->lmac_count)
 		return -ENODEV;
 	lmac_type = rpm->mac_ops->get_lmac_type(rpm, lmac_id);
-	if (lmac_type == LMAC_MODE_100G_R) {
+
+	if (lmac_type == LMAC_MODE_QSGMII || lmac_type == LMAC_MODE_SGMII) {
+		dev_err(&rpm->pdev->dev, "loopback not supported for LPC mode\n");
+		return 0;
+	}
+
 	cfg = rpm_read(rpm, lmac_id, RPMX_MTI_PCS100X_CONTROL1);
 
 	if (enable)
@@ -299,14 +304,6 @@ int rpm_lmac_internal_loopback(void *rpmd, int lmac_id, bool enable)
 	else
 		cfg &= ~RPMX_MTI_PCS_LBK;
 	rpm_write(rpm, lmac_id, RPMX_MTI_PCS100X_CONTROL1, cfg);
-	} else {
-		cfg = rpm_read(rpm, lmac_id, RPMX_MTI_LPCSX_CONTROL1);
-		if (enable)
-			cfg |= RPMX_MTI_PCS_LBK;
-		else
-			cfg &= ~RPMX_MTI_PCS_LBK;
-		rpm_write(rpm, lmac_id, RPMX_MTI_LPCSX_CONTROL1, cfg);
-	}
 
 	return 0;
 }